(a) Field of the Invention
This invention relates to a thread lubricating and sealing composition for rotary shouldered drilling equipment which is useful at elevated temperatures.
(b) State of the Art
Thread compounds are used in every threaded connection in a drill string. Recent increases in drilling activity, deeper drilling, sour gas conditions, temperature extremes, brine drilling fluids and relative scarcity of drilling equipment have placed severe demands on maintaining serviceability and extending the useful life of drilling equipment. As the demands on drill collars and drill pipe have increased, greater demands have been made on thread compounds to adequately protect rotary shouldered joints.
The primary purpose of a thread compound is to protect the threads and shoulders of the tool joints of drill collars and drill pipe during drilling. To protect the threads and shoulders, the thread compound must prevent metal-to-metal contact, provide a leak-proof seal for the drilling fluids, restrict the amount of rotation during makeup and downhole drilling to prevent excessive stresses in the threads, be inert to the corrosive action of compounds in the drilling fluids, resist shocks and vibrations during drilling, break apart easily at torques less than the makeup, and leave no residue or plating on the threads or shoulders upon breakout.
Most thread compounds are produced from low melting, weak, ductile, readily deformed metals combined with non-metallic particles in extremely finely divided condition (powders). When the joint is tightened, the metal and powder particles compact together and fill all the small tool marks, depressions, dents, and imperfections in the joint. The compaction results in a solid rope-like material between the shoulders which gives a firm positive seal and keeps the shoulders apart to prevent galling.
The present invention provides a thread compound designed to operate at elevated temperature in corrosive environments as a thread sealing and lubricating compound. The compound presents no health hazards and does not harm stainless steel fittings. The compound also controls the amount of rotation during makeup, provides resistance to additional downhole makeup and protects the threads against excessive stresses at normal makeup.